Crank shaft



March 12, 1929. AR 1,705,375

CRANK SHAFT Filed April .14, 1928 Patented Mar. 12, 1929.

UNITED STATES PATENT OFFICE.

CRANK SHAFT.

Application filed- April 14, 1928, Serial m5.

This invention relates to crankshafts of the built-up type in which eachcrank pin is carried at its ends in holes in the adjacent pair of crankwebs, a slit extending outwardly from each hole through the portion ofthe crank web surrounding the crank pin so as to enable the web to beclamped about the end of the pin by one or more bolts or the liketending to close ,up the slit.

In previous constructions of crankshaft of this type the slit in thecrank web has extended completely through the part of the websurrounding the crank pin. With such an arrangement, however, the partsof the web on either side of the slit are apt to move relatively to oneanother in a direction parallel to the crankshaft axis due to thestresses set up in operation, and it is the object of the presentinvention to provide a more rigid construction in whichthisundesirableefi'ect will be reduced or eliminated.

To this end, according to the present invention, thev slit which enableseach crank web to be clamped about the adjacent end of the crank pindoes not pass completely through the portion'of the web surrounding thepin but a continuous bridge of metal extends across the outer end of'this slit and joins the portions of the crank web on either sidethereof. The slit must in all cases be of sufiicient length to permitthe flexing of the portions of the crank web on either side thereof bythe bolts or the like to 'clampthe web about the crank pin end.

The-bridge piece may extend substantially directly across the outer endof the slit but preferably in order to reduce the amount of metalrequired on the crank web and to enable the bridge piece to be morereadily flexed, the crank web is provided with a rib: like projection;extending along its outer end parallel withthe slit, the slit being car-1 ried into this rib which thus forms a substantially U-shaped bridgepiece connecting the portions of the web on each side of the slit.

Further, the outer end of the slit may be enlarged to'form a hole sothat the complete slit may be said'to have a somewhat keyhole shape,thus facilitating the drawing together about the end of the crank pin ofthe portions of the web on either side of the slit. Further the portionof each crank web 270,115, and in Great Britain May 2, 1927.

lying between the crank pin and the shaft 1s preferably reduced in widthor waisted so as to render the section of the metal surrounding thepinmore uniform and thus enable it to be flexed more evenly to grip v,

the pin whereby a more rigid clamping of,

the pin in the Web is ensured.

The invention may be applied to a builtup crankshaft of various typesfor example those 1n Wh1ch the shaft lengths which connect ad acentcranks are either formed integral with or formed separately from andvention, the shaft itself being shown in section, and, 1

Figure 2 is a section on the line 2-2 of Figure 1.

In the construction illustrated the crank-- shaft comprises a 'series ofplain shaft lengths A two of which are shown. On the ends of the shaftlengths A are shrunk or otherwise rigidly secured crank webs B, a plainparallel pin 0 constituting a crank pin being carried at its ends inholes B in each adjacent pair of crank webs as shown. The crank webs Bare adapted to be clamped about the ends of the crank pin C and to thisend a slit or cut D is provided in each Web extending from the hole BThe portions of each Web B on each side of the slit D are formed withlugs B through which passes a bolt E provided with a nut E whereby aforce can be exerted tending to close up the slit D and thus clamp theend of the crank pin C firmly in the web. If desired two or more boltholes may be formed in'each lug'B and a corresponding number of clampingbolts provided. The slit D in each crank web B according to thisinvention does not extend completely through the portion of thecrank'web surrounding the crankpin C but is only of such length as toleave a continuous bridge piece of metal extendingv across the outer endof the slit so as to connect the portions of the web on eithersidethereof. Thus the crank Web is conveniently formed beyond the lugs Bon each side of the slit D with a rib-like projection B running parallelwith the slit as shown, the slit being of such length that it extendsinto this rib which thus forms a substantially U-shaped bridge piececonnecting the portions of the crank web on each side of the slit. Theend of the slit D is further conveniently enlarged as shown at D. Theform of the bridge piece thus produced tends to give more readily whenthe nuts E are tightened to clamp the webs about the crank pin.

The crank webs are preferably reduced in width or waisted as shown at Bso as to render the section of the metal surrounding the crank pin Cmore uniform and thus enable the webs to be more evenly flexed by thebolts E whereby a more rigid fixing of the crank pins in the webs tendsto be effected. i

The invention may be applied to built-up crankshafts either'of themulti-throw or single throw type and such crankshafts may be providedwith passages through which lubricating oil can be delivered to thevarious bearing surfaces both for the short shaft lengths A betweenadjacent cranks and for the crank pin or pins C. Thusfor example when,as shown in the drawings, the short shaft lengths A are formed hollow,their ends are conveniently plugged as shown at F while oil passages Gand G pass from the interior of these shaft lengths respectively totheir bearing surfaces A and to the interior of the holes 13 in whichthe crank pins are mounted. Further, passages G are provided in thecrank pins themselves communicating with the oil passages G and adaptedto deliver oil to the crank pin bearing surfaces as shown. Thearrangement is conveniently such that there is a continuous oil passageextending throughout the length of the crankshaft, the end shaft lengthswhich each carry only one crank web being provided with meansrespectively for delivering oil to and withdrawing it from the interiorthereof so that a constant flow of lubricating oil under pressure can bemaintained through the crankshaft to the hearing surfaces.

It is to be understood that thedetails of construction may be variedconsiderably in accordance with the requirements of the engine for whichthe crankshaft is intended without de arting from this invention.

What I c aim as my invention and desire to secure by Letters Patent isk 1. A built-up crankshaft including in combination a plurality of shortshaft lengths, crank webs carried by the ends of these shaft lengths andeach having therein a hole adapted to receive the end of a crank pinwith a slit extending outwardly from this hole through the portion ofthe crank web around it, a bridge of metal formed integral with thecrank web extending across the outer end of each slit so as to join theparts of the web on either side thereof, a crank pin having its endsdisposed respectively in the holes in an adjacent pair of crank Webs andmeans for drawing tothis hole through the portion of the crank webaround it, a bridge of metal formed integral with the crank webextending across the outer end of each slit so as to join the parts ofthe web on either side thereof, a crank pin having its ends disposedrespectively in the holes in'an adjacent pair of crank webs and at leastone bolt serving to draw together the parts of each web on either sideof the slit so as to clamp the webs about the ends of the crank pin.

3. A built-up crankshaft including in combination a plurality of shortshaft lengths, crank webs carried by the ends of these shaft lengths andeach having therein a hole adapted to receive the end of a crank pinwith a'slit extending outwardly from this hole through the portion ofthe crank web around it, a curved bridge of metal combination aplurality of short shaft lengths, crank webs carried by the ends ofthese shaft lengths and each having therein a hole adapted to receivethe end of a crank pin with a slit extending outwardly from this holethrough the portion of the crank web around it, a curved bridge of metalformed integral withthe crank web extending across the. outer end ofeach slit so as to join the parts of the web oneither side thereof, acrank pin having its ends disposed respectively in the holes in anadjacent pair of crank webs and at least one bolt serving to drawtogether the parts of each web on either side of the slit so as to clampthe webs about the ends of the crank 1n. I p 5. A built-up crankshaftincluding in combination a plurality of short shaft lengths, crank webscarried by the ends of these shaft lengths and each having therein ahole adapted to receive the end of a crank.

pin with a slit extending outwardly from this hole through the ,portionof the crank web around it, a bridge of metal formed integral with thecrank web extending across the outer end of each slit so as to join theparts of the web on either side thereof, a crank pin having its endsdisposed respectively in the holes in an adjacent pair of crank webs andmeans for drawing together the parts ofeach web on either side of theslit so as to clamp the web about the end of the crank pin, the portionof each crank web between the crank pin and the short shaft length beingreduced in width as and for the purpose set forth.

6. 'A built-up crankshaft including in combination a plurality of shortshaft lengths, crank webs carried by the ends of these shaft lengths andeach having therein a hole adapted to receive the end of a crank pinwith a slit extending outwardly from this hole through the portion ofthe crank web around it, a curved bridge of metal formed integral withthe crank web extending across the outer end of each slit so as to jointhe parts of the web on either side thereof, a crank pin having its endsdisposed respectively in the holes in an adjacent pair of crank webs andat least one bolt serving todraw together the parts of each web oneither side of the slit so as to clamp the web about the ends of thecrank pin, the portion HARRY RALPH RICARDO.

' of each crank web between the crank pin and v

